<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div>
  <input type="text" v-model="info">
  {{info}}
    <h1>注册表单</h1>
    <form action="">
        用户名:<input type = "text" v-model="user.username"> <br>
        密码:<input type="password" v-model="user.password"> <br>
    </form>
</div>

<script src="https://lf3-cdn-tos.bytecdntp.com/cdn/expire-1-M/vue/2.6.14/vue.min.js"></script>
<script>
  let v=new Vue({
    el:"div",
    data:{
      info:"双向绑定",
        user:{
          username:"",
            password:""
        }

    }
  })
</script>

</body>
</html>